Spatiotemporal ozone concentration variations and their influencing factors in Zhejiang, China, 2018–2022: A geographically and temporally weighted regression

Abstract

In this study, we applied an extended geographically and temporally weighted regression model (GTWR) to explore the spatiotemporal non-stationarity of ground-level ozone (O3) concentrations and the influencing factors in four geographic zones of Zhejiang Province from 2018 to 2022. Our results showed that meteorological conditions and emissions were both important for O3 concentration during this period, and their influences showed significant spatial heterogeneity. Relative humidity (Rh) had negative associations with O3 concentration in all the 90 counties in our study period, and there was a strong positive correlation between maximum air temperature (MaxT) and O3 concentration. The impacts of precipitation on O3 were partly positive in Hangzhou Bay and mostly negative in the other three zones due to the precipitation time. The MaxT had the most significant influence in Hangzhou Bay due to the lowest NO2/VOCs ratio, and NO2 positively influenced O3 except in Hangzhou Bay. The high ground-level O3 occurrence in 2022 resulted from meteorological factors and emissions combined.